1. FIELD OF THE INVENTION
This invention relates in general to sheet sealing methods and devices and, in particular, to a new and useful sheet seal and apparatus for forming a hermetic seal comprising an inner retaining rod having a portion of sheeting to be sealed wrapped therearound and enveloped by a slotted tube having slot edges biased toward each other to urge adjacent portions of the sheeting wrapped around the retaining rod together to form the hermetic seal.
2. DESCRIPTION OF THE PRIOR ART
In packing operations using plastic cover sheetings, it is often necessary to join the edges of sheets to form sealed borders. Among the various methods of forming this seal is a means using a stiff plastic rod which has an accompanying slotted hollow cylinder or tube that closely fits over a portion of the rod. To form a seal, two sheets of plastic sheeting material are placed between the rod and the tube and the seal is held heremetically tight by the close fitting between the rod and the tube. Such an arrangement is disclosed in U.S. Pat. No. 3,149,943.
Disadvantages of the prior art seals using the above method include the requirement of a high degree of precision in the manufactured sizes of the rods and slotted tubes which are used. Since the seal depends on a close fitting of the tube around the rod, any variation in the cross-section diameters of either piece may cause leakage of the seal. Similarly, slight warping of the tube or rod, during shipment or storage for example, may result in a poor seal.